ISi Mr. Ogilby on certain Australian Quadrupeds, 



the same time of increasing the available territory of the country, to comme- 

 morate the event by associating it with his name. I therefore propose to 

 distinguish this interesting species by the name of 



Dipus MiTCHELLii. D. plantis suhpentadactylis ; corpore supra cinereo-fusco, 

 subtus albido ; auriculis magnis ; cauda longissima,Jloccosa. 



This little animal is rather larger than a common mouse, which it is de- 

 scribed as closely resembling in the colour and texture of the fur, being of 

 the same pale ashy-brown tinge on the upper and outer parts, and clearer or 

 more greyish ash beneath. The head is thick and short ; the muzzle blunt ; 

 the upper jaw projecting considerably beyond the lower, and copiously fur- 

 nished with an abundance of long black moustaches ; the eyes are of mode- 

 rate size ; and the ears rather large, erect, rounded at the points, and appa- 

 rently naked. The fore feet are short, the hind excessively long, as in the 

 rest of the genus, the disparity being equally due to the development both of 

 the tibia and tarsus ; the arms, legs, and thighs are covered with fine soft fur, 

 like the rest of the body, but the tarsus and paws are nearly naked, or only 

 covered with very short, adpressed silvery hairs. The tail is considerably 

 longer than the body, naked and scaly towards the origin, but covered, on 

 the terminal half, with long black hairs of a silky quality, which gradually 

 increase in number, and form a middling sized brush at the tip. 



The dimensions of this animal, as taken from a figure as large as life, are 

 as follows. 



Length from the nose to the origin of the tail . 4| inches. 



root of the ear . . 1^ inches. 



Length of the tail 6 inches. 



anterior extremities | of an inch. 



of the tibia If inches. 



■ of the tarsus and toes 1^ inches. 



of the ears | of an inch. 



Breadth of the ears | an inch. 



The anterior extremities appear to have four toes developed, and a small 

 nailless tubercle in place of the thumb, a disposition common not only to 

 other species of Jerboas, but to a great majority of the extensive family of 



